France wants to contact an al-Qaeda group which seized five of its citizens and two others at a uranium mine in Niger last week, a minister has said.
"What we want is, firstly, for al-Qaeda at some point to at least put some demands on the table," Defence Minister Herve Morin told French radio.
A French military team is in Niger to help find the hostages who include a Togolese and a Malagasy national.
The militants killed a French hostage after a failed rescue bid in July.
France's foreign ministry has confirmed that a claim from al-Qaeda in the Islamic Maghreb (AQIM) that it took the latest hostages is genuine.
A new statement attributed to the group appeared on Islamist forums on Thursday, warning France against trying to rescue its citizens.
France's top police officer has warned that the country is facing a "peak" terror threat, such as a conventional bomb attack on a crowded target, and he named AQIM as a particular threat.
The seven hostages were seized on 16 September in raids targeting two French firms employed at the uranium mine near Arlit, northern Niger.
Mr Morin said that, having seen no photographs, video or other evidence to the contrary, he believed the seven hostages were still alive.
"For the time being, our concern is to be able to enter into contact with al-Qaeda, to have some demands... which we do not have," he told France's privately-owned RTL radio station.
"Today we do not have the slightest demand, the only thing we have is the text sent by al-Qaeda to al-Jazeera," he added, referring to the group's initial statement to the Arabic satellite broadcaster.
In that statement, AQIM said it would reveal its demands at a later date.
Mr Morin said the hostages were now "very probably" in northern Mali.
France has sent 80 military personnel to Niger's capital Niamey to help search for the hostages.
They are backed by a long-range Breguet Atlantique aircraft and a Mirage jet equipped with sophisticated monitoring equipment.
In July, AQIM announced it had killed a 78-year-old retired French engineer being held hostage in Mali, after a raid by French and Mauritanian forces failed to free him.
The following month, the Spanish government is believed to have paid millions of euros to free two of its nationals seized by AQIM in Mauritania.
The AQIM statement picked up by US-based monitoring group Site describes the hostage-taking as part of "retaliation" against France by AQIM leader Abdel Moussab Abdelwadoud.
AQIM warned France against attempting a rescue mission "like they had done for Michel Germaneau", the engineer killed in July.
Six AQIM militants were killed in the operation to free Mr Germaneau.
France's national police chief, Frederic Pechenard, urged the public to be more alert about terrorism.
"France is today under threat," he told Europe-1 radio on Wednesday.
"For that matter, French people need to get used to it. We're now facing a peak threat that can't be doubted. There is a specific threat against French interests."
AQIM was "targeting [France] in particular", he said.
"In order to do the maximum possible damage [an attack] would be likely to happen in a place where there are lots of people, which could be the public transit system, a department store or a gathering," Mr Pechenard said.